Pemetrexed-Induced Pseudocellulitis: A Diagnostic Conundrum

Our plain-English summary of Pemetrexed-Induced Pseudocellulitis: A Diagnostic Conundrum, by L.A. Horton, A.B. Lyons, M.C. Kwa, et al (Curēus, 2024).

The study

• Authors: L.A. Horton, A.B. Lyons, M.C. Kwa, M.L. Chaffins, J. Veenstra
• Journal: Curēus
• Published: 2024;16(1):e52114
• Type of article: Case report
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Pemetrexed, an anti-folate, antineoplastic agent, effectively treats various malignancies such as non-small cell lung cancer (NSCLC) and mesothelioma. Here, we report two cases of recurrent pemetrexed-induced lower extremity erythema and edema, one in a 60-year-old male and the other in a 47-year-old male, who were both treated for recurrent cellulitis on multiple occasions before finally being diagnosed with pemetrexed-induced pseudocellulitis (PIP), a rarely reported adverse effect. This is an important diagnostic pitfall for clinicians to be aware of, as early recognition may minimize patient morbidity and prevent unnecessary hospitalization and antibiotic use for presumed cellulitis.

Copyright © 2024, Horton et al.

In plain English

This case report described two men, aged 60 and 47, with metastatic non-small cell lung cancer (NSCLC). Both had repeated episodes of redness and swelling of both lower legs after infusions of the chemotherapy drug pemetrexed. Neither had mesothelioma, and asbestos is not discussed. Both were treated with antibiotics for suspected cellulitis, a skin infection, before being diagnosed with pemetrexed-induced pseudocellulitis, a non-infectious reaction that looks like cellulitis. For the older man, a drug-reaction scoring tool gave a score of 7, which the authors called compatible with a probable adverse drug reaction to pemetrexed. His symptoms improved with prednisone, a steroid. Steroids and compression stockings after later infusions reduced his symptoms but did not fully clear them. The younger man did not improve after five days of antibiotics. A skin biopsy showed swelling with scattered inflammatory cells, and he improved with steroids and compression stockings. He died a month after admission from complications of his cancer. The authors concluded that this rare reaction is often diagnosed late, causing unnecessary pain, hospitalization and antibiotic use.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: case report of two patients
• Who was studied: Two men with metastatic non-small cell lung cancer (NSCLC), aged 60 and 47. The article does not state where or when they were treated.
• Exposure: The exposure was the chemotherapy drug pemetrexed. The 60-year-old received 1.2 g every three weeks for eight months. The 47-year-old received 1.1 g every three weeks over eight months, together with loratinib (spelled as printed). No asbestos exposure is reported.
• Main results:
  • In the 60-year-old, the ALT-70 score for cellulitis was 0.
  • In the 60-year-old, the Naranjo drug-reaction score was 7, which the authors described as compatible with a probable adverse drug reaction to pemetrexed.
  • In the 60-year-old, swelling and redness improved with a prednisone taper.
  • In the 60-year-old, compression stockings and prednisone 10 mg daily for a week after each infusion helped reduce symptoms but did not completely resolve them.
  • In the 47-year-old, five days of broad-spectrum antibiotics did not bring improvement.
  • In the 47-year-old, a punch biopsy showed dermal edema with a sparse interstitial infiltrate of neutrophils and occasional eosinophils.
  • In the 47-year-old, prednisone, triamcinolone cream and compression stockings were followed by improvement.
  • The 47-year-old died one month after admission from complications related to his malignancy.
  • In both patients, the reaction began after about six to eight months of infusions.
• The authors' conclusion: The authors concluded that pemetrexed-induced pseudocellulitis is a rare adverse effect that clinicians should be aware of. Diagnosis is often delayed, causing unnecessary pain, hospitalization and antibiotic use. In their view, it can be managed with systemic steroids, a lower dose, or stopping the drug.

Topics

Medical terms in this study, explained in our Lexicon: Pemetrexed (Alimta), Non-Small Cell Lung Cancer, Mesothelioma, Erythema.

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